The educational content online for Bayesian Networks is not the best. (It's a subtle topic which leads to subtle questions and I'm having a hard time understanding it.)
It is my understanding that every node of a Bayesian Network is a probability distribution and that a node is conditionally independent of its non-descendants given its parents. Is this correct? Can nodes have multivariate distributions? If so, doesn't this mean that every statistical model can be represented as a one-node "bayesian network"? (a trivial one for sure, but still)